This invention relates to a pellet furnace, and more specifically to an apparatus for automatically starting a pellet furnace.
A wood pellet furnace generally comprises a firebox, a fuel storage hopper, and an electrically driven feed mechanism for feeding fuel from the hopper to the firebox. Such a furnace is used to supply heat to a living space in accordance with the setting of a room thermostat, which senses the temperature in the living space. When the room thermostat demands heat, the feed mechanism is energized and fuel is delivered to the firebox. The fuel is ignited by a pilot fire that is maintained in the firebox, and the heat output of the furnace increases. When the thermostat no longer demands heat, the feed mechanism is not continuously energized, but it is energized intermittently to sustain the pilot fire, and accordingly the heat output of the furnace is reduced.
It is usual to extinguish the pilot fire at the end of the heating season. A low limit cut-out switch, which senses the temperature in the firebox, is connected in series with the feed mechanism. As long as a fire is burning in the firebox, the temperature in the furnace will remain above the low limit switch preset level and the switch will remain conductive. When the fire is extinguished at the end of the heating season, the low level cut-out switch becomes non-conductive, preventing supply of current to the feed mechanism. This prevents fuel being supplied to the firebox when there is no fire and guards against possible overflow of the firebox. However, at the beginning of the heating season, when it is time to light the pilot fire, the low level cut-out switch makes it difficult to start the pilot fire, because fuel has to be manually loaded into the firebox and ignited by hand in order to start the pilot fire.